You may fight – you may even start fights – but you may only use deadly force on a foe that is attempting to do you serious harm. Capture is not “serious harm” unless you are already under penalty of death or have a Code of Honor that would require suicide if captured. You never intentionally do anything that causes, or even threatens to cause, injury to the uninvolved – particularly if they are “ordinary folks.”
You may fight – you may even start fights – but you may never do anything that seems likely to kill another. This includes abandoning a wounded foe to die “on his own”! You must do your best to keep your companions from killing, too. If you do kill someone (or feel responsible for a death), you immediately suffer a nervous breakdown. Roll 3d and be totally morose and useless for that many days. During this time, you must make a Will roll to offer any sort of violence toward anyone, for any reason.
You are psychologically unprepared to kill people. Whenever you make a deadly attack (e.g., with a knife or a gun) against an obvious person whose face is visible to you, you are at -4 to hit and may not Aim. If you cannot see the foe’s face (due to a mask, darkness, or distance, or because you attacked from behind), the penalty is only -2, save in close combat. You have no penalty to attack a vehicle (even an occupied one), an opponent you do not believe is a person (including things with Horrific or Monstrous appearance), or a target you can’t actually see (e.g., a set of map coordinates or a blip on a radar screen). If you kill a recognizable person, the effect on you is the same as for Pacifism: Cannot Kill. You have no problem with your allies killing; you may even supply ammo, loaded weapons, and encouragement! You just can’t do the killing yourself.